The following abbreviations are defined as follows:
AG absolute grant
DCH dedicated channel
DL downlink (Node-B to UE)
DPDCH dedicated physical data channel
DPCCH dedicated physical control channel
E-AGCH E-DCH absolute grant channel
E-DCH enhanced uplink DCH
E-DPDCH enhanced DPDCH
E-DPCCH enhanced DPCCH
E-RNTI E-DCH radio network temporary identifier
E-RGCH E-DCH relative grant channel
HARQ hybrid automatic repeat request
HSUPA high speed uplink packet access
MAC medium access control
MAC-d MAC-dedicated transport channel
MAC-e MAC entity that handles the E-DCH
Node-B base station
RG relative grant
RLC radio link control
RLS radio link set
RNC radio network controller
RRC radio resource control
SG serving grant
SI scheduling information
TFC transport format combination
TTI transmission timing interval
UE user equipment, a mobile terminal
UL uplink (UE to Node-B)
Of interest herein is the uplink DCH (EDCH) for packet data traffic in, for example, Release 6 of 3 GPP TS 25.309, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; FDD Enhanced Uplink; Overall Description; Stage 2 (Release 6), which is attached to the incorporated provisional patent application as Exhibit A.
In HSUPA, certain attempts at enhancements are currently approached by distributing some of the packet scheduler functionality to the Node-Bs to provide faster scheduling of bursty, non-real-time traffic than can be provided by the Layer 3 (L3, Network Layer) of the RNC. The idea is that with faster link adaptation it is possible to more efficiently share the uplink power resource between packet data users, as when packets have been transmitted from one user the scheduled resource can be made available immediately to another user. This technique attempts to avoid the peaked variability of noise rise, such as when high data rates are being allocated to users that are running bursty, high data-rate applications.
In the current architecture, the packet scheduler is located in the RNC and therefore is limited in its ability to adapt to the instantaneous traffic, because of bandwidth constraints on the RRC signaling interface between the RNC and the UE. Hence, to accommodate the variability, the packet scheduler must be conservative in allocating uplink power to take into account the influence from inactive users in the following scheduling period. This solution can be spectrally inefficient for high allocated data-rates and long release timer values.
Thus, with E-DCH much of the packet scheduler functionality is transferred to the Node-B, i.e., there is a Node-B scheduler that is responsible for allocating uplink resources.
For transmission of data, the UE selects a TFC that suits the amount of data to be transmitted in a RLC buffer of the UE, subject to constraints on the maximum transmission power of the UE and the maximum power allowed by the Node-B scheduler.
As is currently described in subclause 3.1.2 of 3GPP TS 25.321, V6.8.0 (2006-03), “Medium Access Control (MAC) protocol specification” (attached to the incorporated provisional patent application in its entirety as Exhibit B), the state variable Serving_Grant indicates the maximum E-DPDCH to DPCCH power ratio that the UE 10 is allowed to use for scheduled data in the following transmission. The value in the appropriate state variable is provided to an E-TFC selection function to help in selecting the best format for the upcoming transmission. Possible values are: “Zero_Grant” and numerical values.
For efficient Node-B scheduling, some information is required from the UE, including the UE buffer status (e.g. how full it is), power status (e.g., how much power remains), and priority information regarding MAC-d flows or logical channels that are being used. All of this information is collectively referred to as the SI and is carried in the UL. Based on the SI, the Node-B decides whether to grant or not grant additional resources by responding with (data) rate grant messages in DL serving relative grant (RG) messages or absolute grant (AG) messages.
More specifically, 3GPP TS 25.321 defines UL Scheduling Information in subclause 9.2.5.3 as follows.
The Scheduling Information is located at the end of the MAC-e PDU and is used to provide the serving Node-B with a better view of the amount of system resources needed by the UE and the amount of resources it can actually make use of. The transmission of this information will be initiated due to the quantization of the transport block sizes that can be supported or based on the triggers defined in subclause 11.8.1.6. When a Scheduling Information is transmitted, its contents shall always be updated in new transmissions with the buffer status after application of the E-TFC selection procedure described in subclause 11.8.1.4. The logical channels for which a non-scheduled grant is configured shall never be taken into account when putting together this information. In addition, the RRC may restrict applicability for logical channels for which no non-scheduled grant was configured.
This information includes the following fields:
Highest priority Logical channel ID (HLID): The HLID field identifies unambiguously the highest priority logical channel with available data. If multiple logical channels exist with the highest priority, the one corresponding to the highest buffer occupancy will be reported. The length of the HLID is 4 bits. In case the TEBS is indicating index 0 (0 byte), the HLID shall indicate the value “0000”.
Fields related to amount of available data:
Total E-DCH Buffer Status (TEBS): The TEBS field identifies the total amount of data available across all logical channels for which reporting has been requested by the RRC and indicates the amount of data in number of bytes that is available for transmission and retransmission in RLC layer. When MAC is connected to an AM RLC entity, control PDUs to be transmitted and RLC PDUs outside the RLC Tx window shall also be included in the TEBS. RLC PDUs that have been transmitted but not negatively acknowledged by the peer entity shall not be included in the TEBS.
The length of this field is 5 bits. The values taken by TEBS are shown in Table 9.2.5.3.2.1.
Highest priority Logical channel Buffer Status (HLBS): The HLBS field indicates the amount of data available from the logical channel identified by HLID, relative to the highest value of the buffer size range reported by TEBS when the reported TEBS index is not 31, and relative to 50000 bytes when the reported TEBS index is 31. The length of HLBS is 4 bits. The values taken by HLBS are shown in table 9.2.5.3.2.2. In case the TEBS field is indicating index 0 (0 byte), the HLBS field shall indicate index 0.
UE Power Headroom (UPH): The UPH field indicates the ratio of the maximum UE transmission power and the corresponding DPCCH code power defined in 3GPP TS 25.215 “Physical Layer-Measurements (FDD)”. The length of UPH is 5 bits.
As is currently described in 3GPP TS 25.321 the serving RG messages are taken into account by the UE if there was a scheduled transmission in the previous TTI of the HARQ process. This specified procedure does not address a transmission in the previous TTI where there was SI only.